Ive felt it on my 1994 before. My 96 will be getting a new trans, these will be installed when its donehttp://www.zfdoc.com/c4beamplate.htm

POWERSHIFT TECHNIQUE (hitting the mark) -
Optimize each shift-segment window-of-opportunity by full-cycling the clutch pedal completely to the floor.
Utilize the firewall mat for a springboard to literally bounce the clutch pedal back off of.
The clutch pedal to firewall mat strike point can easily be protected by laying down a few strips of 2" wide high quality electric tape.

How to practice your Shift Reaction Timing:

Out of vehicle -
While standing and balancing on your right leg, raise your left leg 7" up off the floor. Simultaneously tap the floor with the bottom of your shoe tip and snap your right hand fingers (ring/thumb) so as to make one combined noise between the two. Match'em 30 times in a row, and you're dialed in precision shifting.

In vehicle -
Position your seat close enough to the pedals so that depressing the clutch pedal
to the floor is achieved with between 50/50 to 60/40 percent combination of knee/ankle
joint deflection. Shift reaction time seems to tighten up (real nice) when approaching
the 50/50 percent end.
Shift lever movement should initiate to the next gear at the same time you expect to hear the "thunk" of the clutch pedal tapping the mat.

Warning - Shallow clutching is deadly to these transmissions when powershifting.